<template>
  <div class="todo-footer" v-show="total">
        <label>
          <!-- <input type="checkbox" :checked="isAll" @change="checkAll"> -->
          <input type="checkbox" v-model="isAll"/>
        </label>
        <span>
          <span>已完成{{doneTotal}}</span> / 全部{{ total }}
        </span>
        <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
      </div>
</template>

<script>
export default {
  name:'MyFooter',
 props:['todos','checkAllTodo','clearAllTodo'],
 computed:{
  //总数
  total(){
    return this.todos.length
  },
  // 已完成数
  doneTotal(){
    // 此处使用reduce方法做条件统计
/*     const x=this.todos.reduce((pre,current)=>{
      console.log(pre,current);
      return pre+(current.done?1:0)
    },0) */
    // 简写
    return this.todos.reduce((pre,todo)=>pre+(todo.done?1:0),0)
  },
  // 控制全选框
  isAll:{
    // 全选框是否勾选
    get(){
      return this.doneTotal===this.total&&this.total>0
    },
// isAll被修改时set被调用
set(value){
  this.checkAllTodo(value)
}
  }
 },
 methods:{
  // 清空所有已完成
  clearAll(){
    this.checkAllTodo()
  }
 }
}
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>